1. Technical Field
The present disclosure relates to an anvil assembly for use with a surgical stapling device. More particularly, the present disclosure relates to an anvil assembly having a normally tilted anvil head which is usable with an open or a minimally invasive surgical stapling instrument for performing circular anastomosis of hollow tissue organs.
2. Background of Related Art
Anastomosis is the surgical joining of separate hollow organ sections to allow the sections intercommunicate with each other. Typically, an anastomosis procedure follows surgery in which a diseased or defective section of hollow tissue is removed and the remaining end sections are to be joined. Depending on the desired anastomosis procedure, the end sections may be joined by either circular, end-to-end, end-to-side or side-to-side organ reconstruction methods.
In a circular anastomosis procedure, the two ends of the organ sections are joined by means of a stapling instrument which drives a circular array of staples through the organ end sections and simultaneously cores and removes any overlapping tissue to free a tubular passage. In some applications of a circular anastomosis procedure, on anvil rod having an attached anvil head is mounted to the distal end of a surgical stapling instrument shaft prior to insertion of the instrument into the tissue to be anastomosed. However, in other applications, it is preferable to utilize a detachable anvil rod which may be mounted to the instrument subsequent to positioning of the instrument and the anvil assembly within respective tissue sections. In such instances, the stapling instrument and the anvil assembly are separately delivered to the operative site. Each tissue section is then secured to a respective anvil or staple holding component by a purse string suture. The anvil assembly is mounted to the surgical instrument by inserting a mounting portion of the anvil rod within the distal end of the instrument so that a mounting mechanism within the instrument securely engages the rod. Preparation of the tissue sections to be joined and mounting of the anvil rod to the instrument are performed, preferably, using minimally invasive surgical techniques, i.e., under laparoscopic guidance.
A particular difficulty concerning the aforedescribed approach to perform anastomosis of hollow body organs with a detachable anvil assembly, whether the anastomosis is performed laparoscopically or by other conventional open surgical techniques, concerns delivery and placement of the anvil assembly at the desired location within the hollow organ. This difficulty is attributed to, inter alia, the fact that the anvil assembly, particularly, the rigid, immovable anvil head, presents an obtrusive profile which engages the inner wall of the hollow organ during advancement therethrough. In some instances, the dimension of the anvil head is greater than the cross-sectional dimension of the hollow organ through which it must pass. Consequently, advancement of the anvil assembly through the hollow organ can be traumatic and is impeded and possibly prevented. Furthermore, if a surgical procedure is being performed laparoscopically, difficulty with maneuvering the anvil assembly through the hollow organ may require abandonment of such laparoscopic approach and necessitate conversion to a conventional open laparotomy to complete the anastomosis.
In order to reduce the transverse profile of the anvil assembly during placement and removal of the anvil assembly from a hollow organ, anvil assemblies having a tiltable anvil head have been developed. One such anvil assembly is described in U.S. Pat. No. 6,053,390, filed on May 10, 1999, which is incorporated herein by reference in its entirety. The pivotable anvil head is normally locked in the operative firing position. Upon firing the stapling device, the lock is released and the anvil head is forced to the tilted position by a spring.
Despite recent improvements to circular anastomosis instruments, a need still exists for an improved anvil assembly usable with a circular anastomosis instrument which includes an anvil head that is easier to deliver into hollow tissues to be joined, that can be delivered with less contact with such tissues, and also that automatically pivots between tilted and operative positions during delivery and removal of the instrument from the tissues.